Field of the Invention
The invention is directed to a pen needle which may be installed on a drug delivery device, such as a medication pen, including modifications that make the pen needle more cost effective and user friendly.
Description of the Related Art
Pen needles are widely used in medication delivery systems for self-administered injectable drugs. The pen needles that are commonly used have a single stainless steel cannula extending through the needle-bearing hub. The non-patient end of the needle pierces the closure of the drug storage compartment of the medication pen while the patient end of the needle is adapted for insertion into the patient's tissue. Thus, in the conventional pen needle, since a single cannula is used, both ends of the cannula have the same inner and outer diameter. A problem exists in that thinner gauge needles which may be preferred for patient comfort do not reliably pierce the septum of the medication compartment when the pen needle is installed on the medication pen.
Another drawback of the commonly available pen needles is that they do not provide the user with an indication that the needle has reached the optimal penetration depth. The user relies on subjective sensation of pain when performing an injection to determine the depth of penetration, which may result in too much or too little penetration. An injection that is too deep may cause unnecessary pain when the needle is pressed too hard against the body, while an injection that is not deep enough may result in improper dosing. Thus, there is a need for pen needles that provide penetration depth indication.
These and other drawbacks of the prior art are achieved according to the present invention as described in the following specification and claims.